1. Field of the Invention
This invention relates to devices which interlock circuit breakers to preclude two circuits from being closed simultaneously. Specifically, this invention relates to a manual operator for an electronically controlled interlock assembly.
2. Background Information
There are a number of applications where it is required that the operation of two circuit breakers on a panel board be coordinated such that only one circuit breaker can be in the closed, operating position at one time. One such application is providing a power-consuming load with electrical power from either of two different sources, such as a commercial power system and an auxiliary supply. It is imperative in such applications that only one circuit breaker be in the closed, operating position at one time.
One common circuit breaker configuration has a rectangular body and a pivoting, actuating handle mounted medially thereon. The actuating handle travels in a direction parallel to the longer sides of the rectangular circuit breaker body. Circuit breakers are typically mounted with the switches operating in the vertical direction, typically with the upward position being the closed, operating position.
U.S. Pat. No. 5,081,367 discloses an interlock for circuit breakers coupled to a primary and an auxiliary power source. It is known to have a first and second circuit breaker, each with a pivoting handle, mounted in a spaced relation on a panel. The circuit breakers are structured so that when the handle is in a first position, the circuit breaker is open and when the handle is in a second position, the circuit breaker is closed. Additionally, when the handle of a circuit breaker is in a medial position, the circuit breaker is open. The first circuit breaker may be coupled to the primary power source. The second circuit breaker may be coupled to the auxiliary power source.
A rocking bar interlock assembly is mounted on a support above the circuit breakers. The rocking bar assembly includes a mounting plate, a pivot mounted thereon, and a rocking bar. The rocking bar is coupled to each circuit breaker handle and to the pivot. The pivot is disposed between the spaced circuit breakers. A first, distal end of the rocking bar is coupled to the second circuit breaker handle. The second, proximal end of the rocking bar extends beyond the first circuit breaker and is coupled to a motor. The rocking bar is structured to rotate the rocking bar in a seesaw fashion about the pivot. That is, the motor has a rotary output shaft. A rigid member, having a distal end, extends from, and is perpendicular to, the shaft. A pin is located on the rigid member distal end. The pin extends in a direction generally parallel to the axis of the shaft. The pin is coupled to the rocking arm. The motor is structured to move between a first and second position which are disposed, generally, 180 degrees apart. For description purposes only, the first position shall be described as the 12:00 o""clock position and the second position shall be described as the 6:00 o""clock position. The motor rotates the shaft in a clockwise direction. When the pin is in the 9:00 o""clock position, the pivot, the pin and the shaft lie generally along a single line.
In operation, when the motor is in the first, 12:00 o""clock position, the first circuit breaker is in a closed position and the second circuit breaker is in an open position. As the motor rotates to the 9:00 o""clock position and the rocking arm rotates about the pivot, both circuit breakers are moved into the medial, open position. As the motor further rotates into the second, 6:00 o""clock position, the first circuit breaker is moved into the second, open position and the second circuit breaker is moved into the first, closed position. This procedure is reversed when the motor moves between the 6:00 o""clock position and the 12:00 o""clock position.
The motor for this type of interlock includes an electronic brake device. The brake device is structured to lock the motor in either the 12:00 o""clock or the 6:00 o""clock position. When power is applied to the brake device, the brake is released and the motor may rotate. The disadvantage to this interlock is that, when the electronic control of the brake device becomes inhibited, the motor cannot be rotated. Thus, to switch between the primary and auxiliary power source, the interlock device must be removed.
There is, therefore, a need for a manual control for an electronically operated interlock device.
There is a further need for a manual control that can be operated with one hand so that the other hand may move the interlock rocking bar.
There is a further need for a manual control that is compatible with existing technology.
These needs, and others, are satisfied by the invention which is directed to a manual operator assembly for a motor driven interlock. The interlock assembly includes a rocking arm that is coupled to a motor. The motor includes a brake assembly that prevents the motor from rotating. The brake assembly may be controlled electronically. The brake assembly also includes brake release pedal that is external to the motor. The manual operator assembly actuates the brake release pedal so that the motor is unlocked and the rocking arm may be moved manually.
The manual operator assembly includes a brake release lever, a shaft, a spring return, and a cam. The interlock rocking bar is mounted on a support plate. The circuit breakers and motor are disposed below the support plate. The manual operator lever is disposed above the support plate. The manual operator shaft extends through the support plate and is coupled to the cam. The cam is positioned adjacent to the brake release pedal. The spring return biases the cam away from the brake release pedal. The manual operator assembly also includes a knob coupled to the rocking arm.
In operation, the motor will be locked in one position by the brake assembly. Typically, the brake assembly is released via an electronic signal. However, if the electronic controls are not operational, a user may operate the interlock using the manual operator. The user rotates, and holds, the brake release lever causing the cam to actuate the brake release pedal. With the brake release pedal actuated, the motor assembly is no longer locked. The user then grasps the knob on the rocking arm and moves it between the first and second positions. Once the rocking arm is in the final position, the user releases the brake release lever, which is then moved out of contact with the brake release pedal by the return spring. Once the brake release pedal is free, the brake assembly re-engages and the motor is locked again.